Make the Patties: In a mixing bowl, combine ground beef, salt, pepper, thyme, egg, and breadcrumbs. Mix thoroughly with your hands or a fork.
Shape the Patties: Divide the mixture into 4 equal pieces, roll them into balls, and flatten them into large, thin patties on a parchment-lined tray. Press a slight dent in the center of each patty.
Cook the Patties: Heat oil in a large skillet. Cook the patties for about 3-4 minutes per side, or grill/oven-bake them to your preferred doneness.
Prepare the Sauce: In a small bowl, mix together mayo and ketchup to create the sauce.
Assemble the Burgers: Spread about a tablespoon of mayo sauce on the bun base, add lettuce, the cooked patty, a slice of dill pickle, and cheese cut to look like teeth. Drizzle ketchup on top to resemble "blood" and cover with the bun.
Add the Olives: Stick 2 large green olives onto toothpicks and insert them into the bun for spooky eyes. Enjoy!